Filter for absorbing water

ABSTRACT

A filter ( 2 ) comprising a body ( 4 ), an inlet ( 6 ) for a liquid passing into the body ( 4 ), an outlet ( 8 ) for the liquid passing out of the body ( 4 ), and a foam material ( 10 ) in the body ( 4 ) for filtering the liquid as the liquid passes through the body ( 4 ) and also for absorbing water in the liquid.

This invention relates to a filter, for example an oil filter.

Filters for filtering different types of liquids are well known. Thus,for example, oil filters are well known and used for filtering oil forequipment such for example as hydraulic circuits and engines. Oftenequipment utilising oil and oil filters is used in temperatureconditions which are hot during the day and substantially colder atnight. Such a drop in temperature at night can lead to condensation ofwater from the atmosphere and this water can be taken up by the oil.There are many instances where it is not acceptable to have more thantrace elements of water in oil. Thus, for example, equipment such astractors and earth moving equipment often utilises closed hydrauliccircuits. Too much water in the hydraulic circuits can lead to the oilbubbling or boiling, and it can also lead to pistons prematurelycollapsing and seals prematurely failing. In addition, the hydrauliccircuits tend to suffer from an accumulation of dirt which manifestsitself as silt and which can damage component parts of the equipment.Liquids used as engine fuels also should not contain water.

It is an aim of the present invention to provide a filter which is ableto reduce the above mentioned problems.

Accordingly, in one non-limiting embodiment of the present inventionthere is provided a filter comprising a body, an inlet for a liquidpassing into the body, an outlet for the liquid passing out of the body,and a foam material in the body for filtering the liquid as the liquidpasses through the body and also for absorbing water in the liquid.

The filter of the present invention is advantageous in that the foammaterial filters the liquids and also absorbs the water in the liquid.If the liquid, for example oil, also contains silt, then this silt mayalso be removed. The foam material is advantageous in that it contains alarge volume of air and thus has a large operative surface area. Thefoam material may be regarded as having a honeycomb structure. The foammaterial may be 98% by volume air. The structure of the foam materialthus gives very effective filtration and water absorbing.

The equipment using the filtered and purified liquid may be hydrauliccircuits for various devices, including tractors and earth movingequipment, with such circuits being closed circuits. Alternatively, theequipment may be engines such for example as internal combustion engineswhere oil is supplied to the engines in what may be regarded as an opencircuit.

Generally, the filter can be a filter for any suitable and appropriatepurpose. Thus, for example, the filter may be used for filtering a fuelin order to remove water from the fuel. The filter may be used to filterwater from various types of fuel including petrol, but especiallyincluding diesel fuel and methanol where water in the diesel fuel andmethanol can present something of a problem. If desired, the filter maybe used for removing water from gases.

The filter may be produced to be smaller than known filters ofcomparable filtering capacity. Thus, the filter of the present inventionmay be of especial use in engines where space is a problem.

If desired, the filter may be used in the fuel line between a fuel tankand a large diesel engine, for example engines as employed inexcavators, large marine vehicles, and large electrical generatorapparatus.

The foam material is preferably a woven foam material.

The foam material may be a polymer material.

The foam material may be a foam material which is not hygroscopic. Apresently preferred such material is that manufactured by the CamelotCompany. Because the foam material is not hygroscopic, it does notbecome wet in humid atmospheres and so there is no need to protect thefoam material, for example by encapsulating it, from the effects of theatmosphere. An alternative less preferred foam material which can beused and which is in fact hygroscopic is that sold under the trade markLuquafleece by BASF Superabsorbents Ltd. of Birkenhead, United Kingdom.

The foam material may be in pieces which are positioned in the body.

Alternatively, the foam material may form part of a cartridge which ispositioned in the body. Advantageously, the cartridge may be adisposable cartridge so that the body of the filter can continue to beused with different cartridges. Used cartridges can simply beingreplaced by new cartridges. With such an arrangement, a pack could besold with the filter comprising the body, the inlet and the outlet, anda plurality of the disposable cartridges for use with the same body. Ifdesired however, the cartridge could be a permanent cartridge.

The cartridge, for example the disposable cartridge, may include asupport member for the foam material. The support member may have aplurality of apertures along its length for enabling the liquid to passthrough the support member.

In one embodiment of the invention, the foam material is positionedaround the outside of the support member. In this embodiment of theinvention, the foam material is preferably in sheet form and it iswrapped around the outside of the support member.

In an alternative embodiment of the invention, the foam material ispositioned inside the support member. In this case, the foam materialmay be in sheet form or in the form of pieces. The filter may includeend screen members for retaining the foam material in the supportmember.

The filter may include a non-return valve. The non-return valve may bepositioned in an end part of the filter.

The filter of the present invention may be of any suitable andappropriate construction. The body of the filter may be made of aplastics material. Any suitable and appropriate plastics materials maybe employed. The plastics materials may be transparent for see-throughpurposes, or non-transparent. The body of the filter may also be made ofa metal.

The filter may be one having a separate inlet and outlet. The separateinlet and outlet are preferably formed for push on hose connections heldin place by clips such as jubilee clips. Other formations may beemployed so that, for example, the separate inlet and outlet may be forreceiving screw fittings or snap fittings. The filter may alternativelyhave a single combined inlet and outlet, and such a filter may be one inwhich the combined inlet and outlet is an internally threaded aperturefor enabling the filter to be a screw threaded connection to a circuit,for example a hydraulic circuit.

It may be advantageous to know when the filter is blocking or a systemcontaining the filter is blocking. Pressure sensing means such forexample as a pressure differential gauge can be built in, so that a usercan constantly monitor system conditions. The monitoring may be effectedlocally, or even remotely, for example for hospital emergency standbygenerators.

The use of the foam material is also advantageous in that the foammaterial does not dictate the shape of the filter or component parts ofthe filter. Thus the filter can be made in a wide variety of shapes.This can be advantageous in causing the filter to be made in a shape,for example a star shape, that gives an oil cooling function. With sucha shape, the filter can act as an oil cooler. With sufficient oilcooling from the filter, hitherto used radiators could be reduced insize or even dispensed with.

Embodiments of the invention will now be described solely by way ofexample and with reference to the accompanying drawings in which:

FIG. 1 is a cross section through a first oil filter;

FIG. 2 is a perspective view of the oil filter shown in FIG. 1;

FIG. 3 is an exploded view of a second oil filter;

FIG. 4 is a an exploded view of a third oil filter;

FIG. 5 is a perspective view of a part of the third oil filter shown inFIG. 4.

Referring to FIG. 1, there is shown an oil filter 2 comprising a body 4,an inlet 6 for oil passing into the body 4, an outlet 8 for oil passingout of the body 4, and foam material 10 in the body 4 for filtering theoil as it passes through the body 4, and also for absorbing water andsilt in the oil. The water and the silt are generated in the oil duringuse of the oil filter in a hydraulic circuit for equipment (not shown).The oil filter 2 is advantageously able to sit direct in a hydraulicfuel tank (not shown) if desired. The oil filter 2 is also able to beused for road vehicle engines.

The foam material 10 is a woven polymer foam material. The woven polymerfoam material is non-hygroscopic. The foam material 10 is in smallpieces as shown.

The body 4 is made of a plastics material. The body 4 comprises a mainbody part 16 and a cap part 18 which screws to the main body part 16 viascrew threads 20. The cap part 18 may have a grip portion 22 for helpingthe cap part 18 to be tightened and un-tightened from the main body part16.

An oil seal 24 is provided for preventing loss of oil from between themain body part 16 and the cap part 18 when the oil filter 2 is operatingunder hydraulic pressure.

The main body part 16 and the cap part 18 may be made as mouldings, forexample from glass reinforced nylon.

The oil filter 2 may includes a non-return valve (not shown). Thenon-return valve acts as an anti-drain valve.

A screen 26 are positioned as shown in order to retain the pieces of thefoam material 10 in the body 4

Reference will now be to the following Example in which new oil withvarious additives was twice filtered through an oil filter 2 of theconstruction shown in FIG. 1. A control batch of the oil was passedthrough an oil filter as shown as FIG. 1 but without the foam material.Another portion of the oil was passed through the oil filter 2 exactlyas shown in FIG. 1, that is with the foam material 10. The resultsobtained are given hereinbelow. TABLE 1 OIL PASSED THROUGH FILTER WITHNO FOAM MATERIAL Additives New Oil Filtered Once Filtered Twice Iron 5 44 Chromium 0 0 0 Aluminium 0 0 1 Copper 1 1 1 Lead 4 5 4 Nickel 0 0 0Tin 0 0 0 Manganese 0 0 0 Titanium 0 0 0 Silver 0 0 0 Molybdenum 0 0 0Zinc 405 403 319 Phosphorus 270 269 263 Calcium 38 35 35 Barium 0 0 0Magnesium 1 1 1 Silicon 1 2 1 Sodium 3 6 6 Boron 1 1 1 Vanadium 0 0 0Water 163 ppm 123 ppm 209 ppm

TABLE 2 OIL PASSED THROUGH FILTER WITH FOAM MATERIAL (FIGS. 1 and 2).Additives New Oil Filtered Once Filtered Twice Iron 0 0 0 Chromium 0 0 0Aluminium 0 0 0 Copper 0 0 0 Lead 0 2 1 Nickel 0 0 0 Tin 0 0 0 Manganese0 0 0 Titanium 0 0 0 Silver 0 0 0 Molybdenum 0 0 0 Zinc 426 441 547Phosphorus 269 266 281 Calcium 26 27 28 Barium 0 0 0 Magnesium 0 1 1Silicon 4 5 4 Sodium 0 0 0 Boron 0 0 0 Vanadium 0 0 0 Water 84 ppm 91ppm 84 ppm

It will be noted from Table 1 that the additives of zinc, phosphorus andcalcium are at an acceptable level, both in the new oil and after theoil had been filtered twice. However, the amount of water in the new oilwas 163 ppm but this increased to 209 ppm at the second filtering. Thisamount of water in the oil was not acceptable.

It will be noted from Table 2 that the additives of zinc, phosphorus andcalcium remained at acceptable levels and also that the water remainedat an acceptable level. More specifically, the water content of the oilafter the second pass through the oil filter 20 was exactly the same asthe water content of the new oil, namely 84 ppm. Thus the oil filter 2with the foam material 10 maintained the water content of the oil aftertwo passes through the oil filter 2 at exactly the same level of partsper million as it was initially in the new oil. Further, the use of thefoam material 10 did not adversely affect the additives in the oil andthus the additives were able to perform the function which they wereintended to by the oil manufacturer. Also, the use of the foam material10 absorbed silt in the oil, this not being shown in Table 2. The foammaterial 10 acts as a purifier to purify the oil from the water and thesilt.

The filter 2 is also advantageous in that it uses snap-on fittings forthe inlet 6 and the outlet 8. The snap-on fittings are cheaper thanscrew threads to manufacture, they require simpler tooling, and they areeasier to use than threaded fittings. With threaded fittings, there is atendency for people fitting the filters to over-tighten the threadsand/or to cross thread the threads.

The filter 2 is also advantageous in that the screens 26 can easily belocated adjacent the inlet 6 and the outlet 8 by welding. The weldingmay be ultrasonic welding, for example where the body 4 and theillustrated lid 4 are made of plastics materials.

If desired, the oil filter 2 can be made such that the body 4 and/or thelid 4 are made of a transparent plastics material so that it is possibleto see inside the oil filter 2 and see how the foam material 10 isworking.

The oil filter 2 may be manufactured as a cheap, easily installed andhighly efficient disposable filter. By removing water from the oil,damage to equipment can be avoided, which in turn helps to reducewarranty claims for equipment manufacturers.

Referring now to FIG. 3 there is shown a filter 28 comprising a body 30,an inlet for liquid passing into the body 30, and outlet for liquidpassing out of the body 30, and a foam material 32 for filtering theliquid as it passes through the body 30 and also for absorbing water inthe liquid. The filter 28 shown in FIG. 3 is advantageously employed asa filter for an engine for a road vehicle such for example as car.

The foam material 30 is a woven polymer foam material. The foam material30 is in sheet form which is wound around a support member 34. Thesupport member 34 with the foam material 30 forms a disposable cartridgewhich can be replaced in the body 30 when it becomes used up.

The support member 30 has top and bottom flanges 36, 38 respectively forhelping to locate the wound foam material 32, and also for ensuring thatthe foam material 32 does not slip longitudinally on the support member34.

The support member 34 has a plurality of apertures 40 along itslongitudinal length. These apertures enable the filtered liquid, forexample filtered oil, to pass through the wall of the support member 34and be filtered by the foam material 32. The flow and return can be ofany suitable and appropriate way so that the material being filteredcould flow radially outwardly or radially inwardly with respect to thesupport member 34.

Also shown in FIG. 3 is a bottom part 42 of the filter 28. The bottompart 32 has an internally screw-threaded portion 44 which screws to anexternally screw-threaded portion 46 of the body 30. Oil flow throughthe filter 28 is shown by arrow 48, and oil return through the oilfilter 28 is shown by arrow 50. The oil flow shown by arrow 48 is suchthat the oil passes through apertures 52 in the bottom part 42. Theseapertures 42 are advantageously covered with a diaphragm (not shown).Thus, when the engine or other piece of apparatus is not operating, thediaphragm retains oil in the oil filter 28 because it prevents the oilfrom running out through the apertures 52. Thus, at start-up conditions,the oil filter 28 is always full of oil and there is no period when theengine could be starved of oil for lubrication purposes.

FIG. 3 shows schematically part of the engine 54. The engine 54 isprovided with a threaded stud 56 onto which the oil filter 28 isscrewed.

FIG. 4 shows a third oil filter 58 which also employs a replaceablecartridge similar to that shown in FIG. 3. Similar parts have been giventhe same reference numerals for ease of comparison and understanding.

In FIG. 4, there is shown a top part 60 which has a threaded portion 62for enabling the top part 60 to be screwed into position on the top ofthe body 30 of the oil filter 58.

FIG. 5 is a perspective view of the top part 60 and it will be seen thatthe top part 60 has a boss 64 for receiving a pressure relief valve (notshown). The pressure relief valve is employed for ensuring that, in theevent of a blockage, the pressure relief valve will enable oil still tobe passed to the engine.

It is to be appreciated that the embodiments of the invention describedabove with reference to the accompanying drawings have been given by wayof example only and that modifications may be effected. Thus, forexample, the bodies of the oil filters are preferably made of a plasticsmaterial so that the oil filters can be recycled. The oil filters canhowever be made of other materials such as metals if desired. Thefilters may be such that it is secured in position by means other thanscrew threads. The filters can be mounted in any suitable andappropriate position relative to a hydraulic circuit.

Where a pressure relief valve is employed, then the pressure reliefvalve may comprise a ball valve and a spring for biasing the ball valveto a normally closed position against a valve seat. If the filter meansshould become blocked with filtered impurities from the oil, then theoil may not be able to get through the filter. Any engine or other pieceof equipment requiring the oil could thus be starved of the oil. If theoil filter becomes blocked, then pressure will rise in the oil filter.This will cause the oil to flow through apertures and force the ballvalve off its seat. A bore will then be opened and the oil can flowalong the passageway to the outlet. Thus, the oil will still be providedto an engine or whatever else requires the oil, even in the event of ablockage in the filter.

The pressure relief valve is advantageously located as shown in a cappart of the oil filter. Thus the cap part can be removed from the mainbody part in order to allow the foam material, for example in the formof a cartridge to be replaced. The use of replacement cartridges canthus be effected without having to throw away the main body or the cappart of the filter. These parts are relatively expensive, especiallywhen they contain the pressure relief valve. Thus the oil filter of thepresent invention can be extremely cheap to maintain. Liquids other thanoil may be filtered.

If desired, in the filter of the invention, a magnet may be employed toattract ferrous particles out of the oil. If a magnet is employed, thenthe magnet is preferably located in the cap or lid of the filter. Thusthe magnet can easily be retained if the filter is opened up andprovided with new water absorbing polymer material. The cap or lid maybe a bayonet fitting to the main body instead of being a screw threadedfit.

In FIGS. 1 and 2, the inlet 6 and the outlet 8 may be reversed. Ifdesired, the oil filter 2 may be rotated through 90° from the positionshown in FIG. 1 so that the oil filter 2 may be installed horizontallyrather than vertically as shown in FIG. 1.

1. A filter comprising a body, an inlet for liquid passing into the body, an outlet for the liquid passing out of the body, and a foam material in the body for filtering the liquid as the liquid passes through the body and also for absorbing water in the liquid.
 2. A filter according to claim 1 in which the foam material is a woven foam material.
 3. A filter according to claim 1 in which the foam material is a polymer foam material.
 4. A filter according to claim 1 in which the foam material is in pieces which are positioned in the body.
 5. A filter according to claim 1 in which the foam material forms part of a cartridge which is positioned in the body.
 6. A filter according to claim 5 in which the cartridge is a disposable cartridge.
 7. A filter according to claim 5 in which the cartridge includes a support member for the foam material.
 8. A filter according to claim 7 in which the support member has a plurality of apertures along its length for enabling the liquid to pass through the support member.
 9. A filter according to claim 7 in which the foam material is positioned around the outside of the support member.
 10. A filter according to claim 9 in which the foam material is in sheet form and is wrapped around the outside of the support member.
 11. A filter according to claim 7 in which the foam material is positioned inside the support member.
 12. A filter according to claim 11 in which the foam material is in sheet form or is in the form of pieces.
 13. A filter according to claim 12 and including end screen members for retaining the foam material in the support member.
 14. A filter according to claim 1 and including a non-return valve.
 15. A filter according to claim 14 in which the non-return valve is positioned in an end part of the filter.
 16. A filter according to claim 1 in which the outlet is an internally threaded outlet for enabling the filter to be a screw threaded connection to a circuit. 